1. Field of the invention
This invention relates generally to the field of combinating tumbler locks, and more particularly to tumbler locks used on safe doors and the like.
2. Description of the Prior Art
There are many combinating tumbler handle locks in the prior art which can be used on a safe door or the like. However, many of these have drawbacks which make them undesirable.
A common problem with combinating tumbler locks is that they are vulnerable to being forced open by individuals not possessing a key. When the handle lock is used in conjunction with a combination lock on a safe door, this could create undesirable security problems. For example, in an office environment it is often inconvenient for employees to dial the combination each time they wish to open the safe. Therefore, frequently, the safe's combination lock is unlocked at the beginning of the day and for the remainder of the day the safe is opened and closed using only the key-actuated handle lock. While this arrangement may be convenient, it places the contents of the safe in a vulnerable position. With typical combinating tumbler handle locks, the handle is rigidly connected to the lock plug and if a significant force is exerted on the handle when the tumblers are engaged with the lock shell the tumblers may shear within the lock shell. Once the tumblers have sheared, the lock plug might rotate freely within the lock shell and the safe can be opened without the use of the key. Worse yet, application of such a force may result in a jamming or breaking of the handle, resulting in lockout.
Another common problem with combinating tumbler handle locks is that the handle rotates loosely after the key has been inserted in the lock. This loose rotation can result in difficulty in locating the open and closed positions of the handle lock. In addition, the loose rotation may make it difficult to keep the handle accurately aligned in the open and closed positions after the key has been inserted. Thus, this loose rotation makes these locks inconvenient to use.